Pedestrian protection apparatus for motor vehicles

ABSTRACT

A pedestrian protection apparatus particularly adapted for motor vehicle front end structures for mitigating injuries of pedestrians struck by the vehicle. The apparatus incorporates a front grill which is moveable between extended and retracted positions. While it is in its extended position, the grill is designed to absorb energy from a pedestrian impact to reduce pedestrian injuries. The position of the grill is controlled by an actuator which responds to control inputs such as vehicle speed.

FIELD OF THE INVENTION

This invention relates to an apparatus for reducing pedestrian impactinjuries caused by motor vehicles striking a pedestrian.

BACKGROUND OF THE INVENTION

Substantial advances have been made in recent years in the improvementof impact protection for motor vehicle occupants. Various strategiesincorporating active and passive restraint systems have been implementedin motor vehicles. Sophisticated energy absorbing structures aredesigned into motor vehicles with an eye toward reducing occupantinjuries.

While much progress has occurred in improving the safety of motorvehicle occupants in impact conditions, one segment of victims of motorvehicle impacts has been largely unaddressed; namely, pedestrians. Motorvehicle impacts with pedestrians remain a serious concern, taking thelives of many each year throughout the world and causing severeinjuries.

Certain strategies are known to reduce the severity of pedestrianimpacts. For example, it is known in the art to provide a motor vehiclewith a front hood that raises a predetermined distance to provide forenergy absorption in anticipation of a vehicle impact with a pedestrian.However, in order to take advantage of such hood lifting technologies,the vehicle must be designed such that the hood must not rise above apredetermined height. Otherwise, the hood lifting approach does notbenefit typical pedestrians. Moreover, shorter pedestrians, includingchildren, receive little benefit from hood lifting systems which aredesigned to reduce the severity of impact of the upper body of thepedestrian as a pedestrian's body is rotated by the initial impact withthe lower torso.

Another technology for addressing pedestrian impacts has further beenproposed which incorporates an inflatable energy absorbing structuredeployed from the front end of the vehicle based on an anticipatedimpact. This approach has a substantial disadvantage that it must bedeployed in an irreversible process in response to a detected impendingimpact. This requirement imposes significant design and cost penalties.

It is also known in the art to provide an extendable-type bumperarrangement for vehicles which, in anticipation of an impending vehiclecrash, or in response to a predetermined speed threshold, will extend apredetermined distance from an unextended position. However, it is notedthat such extendible-type bumper arrangements are designed to protecteither the vehicle occupants or the vehicle. It is noted that in orderto attenuate the energy of a first vehicle striking a second vehicle orthe like, the energy absorption requirements are substantially differentthan would be optimal to attenuate the energy of a vehicle impacting apedestrian with an aim toward reducing injury to the pedestrian. Infact, it should be recognized that most of the extendible bumper-typeapproaches for vehicle impact protection may pose a risk of greater harmto a pedestrian than a conventional bumper.

It is the lack of protection for pedestrians and, in particular, shorterpedestrians in combination with high hoods and the need for pre-crashhuman discrimination sensing and non-pedestrian friendly extendedbumpers that are addressed by the present invention. This inventionprovides an improved pedestrian protection apparatus. The apparatus hasparticular use in mitigating harm otherwise caused to pedestrians whenstruck by an automotive vehicle. The invention incorporates a grillcovering of the front end structure of a vehicle which is actuated toextend from the vehicle exterior based on commands from an electroniccontrol unit.

Various strategies for deployment of the system of this invention may beimplemented. For example, merely by sensing the speed of the vehicle,the grill could be automatically extended without intervention by avehicle occupant whenever the vehicle is moving at city traffic speedswhich would be typical in instances of pedestrian impact. The actuatorsfor the grill may be designed to have energy absorbing characteristics,thus providing an energy absorbing “soft” grill structure which strikesthe pedestrian. The extended position of the grill allows substantialenergy absorption to occur, reducing pedestrian injuries. The extendedgrill may also secondarily act as a sensor for vehicle impacts. In theextended position, an impact load acting on the grill can be used todeploy additional pedestrian impact mitigation systems, such as hoodlifting technology or inflatable energy absorbing structures.

Additional benefits and advantages of the present invention will becomeapparent to those skilled in the art to which the present inventionrelates from the subsequent description of the preferred embodiment andthe appended claims, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of the front end structure of a motorvehicle incorporating an extendible grill in accordance with thisinvention showing the grill in a retracted position shown in full lines,and an extended position shown in phantom lines;

FIG. 2 is a simplified illustration of a mechanical actuator of the rackand pinion variety used to extend and retract the grill; and

FIG. 3 is a schematic diagram of a control system for the pedestrianimpact protection system in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, pedestrian protection apparatus 10 is shownintegrated into a motor vehicle front end structure 12. Pedestrianprotection apparatus 10 incorporates an extendable grill 14 which is anenlarged frame-like structure having appropriate openings for vehiclehead lights shown as opening 15, and other open areas to satisfy airintake, cooling, and styling requirements. Preferably, the outerperimeter of grill 14 substantially encompasses the forward surface ofmotor vehicle front end structure 12 (i.e. the frontal, generally “flat”surface of the vehicle subject to striking a pedestrian). Grill 14 couldbe formed from various materials including metals and polymers with anaim of reducing impact injury through deformation and energy absorption.

Grill 14 is designed such that it is capable of stroking between aretracted position shown in full lines in FIG. 1 and a forwardlyextended position extending from the vehicle as shown in phantom linesin FIG. 1.

FIG. 2 illustrates one example of an actuator 16 capable of moving grill14 between its retracted and extended positions as shown in FIG. 1.Pinion gear 18 is driven through an appropriate electrical or hydraulicmotor and rotates causing toothed rack 20 to stroke in the lineardirection as indicated by the arrows of FIG. 2. Toothed rack 20 isconnected to grill 14. In a preferred implementation, two or more ofactuators 16 would be used for controlling the position of grill 14.

Since a primary function of pedestrian protection apparatus 10 is toabsorb impact energy with the pedestrian, actuators 16 may designed toprovide energy absorption during impact. For example, the teeth oftoothed rack 20 may be designed to shear in response to an impact loadwhile the teeth of pinion gear 18 would maintain their integrity.Numerous other strategies for energy absorption could be implemented,including, using viscous or other energy absorbing mechanical damperassociated with pinion gears 18, mounting the whole structure ofactuator 16 to its own energy absorbing structure, or using an energyabsorbing structure connected directly with toothed rack 20 thatresponds to provide dampening in the event that toothed rack 20 isaccelerated.

As an approach toward simplifying the control strategies for pedestrianprotection apparatus 10, its deployment may be, in one example,controlled entirely in response to vehicle speed inputs. FIG. 3illustrates diagrammatically a control system in which vehicle speedsensor 22 provides vehicle speed inputs to electronic control unit (ECU)24. Vehicle speed sensor 22 would likely comprise the speed sensorspresent on modern motor vehicles used for controlling other functions ofthe vehicle including power train control systems, anti-lock brakesystems (ABS), and vehicle stability control systems. ECU unit 24provides inputs for grill actuator 26 which provides a driving controlfor pinion gear 18 of actuator 16. In each case, it is preferred thatthe system operate automatically without direct intervention by anoccupant of the vehicle.

Various control strategies could be employed based on the output fromvehicle speed sensor 22. The following Table 1 illustrates one suchcontrol approach. TABLE 1 Speed Signal Actuator Position Action #1Speed > 10-35 mph Retracted Extend Actuator Extended No Change #2 Speed< 8 mph Retracted No Change Extended Retract Actuator #3 Speed > 37 mphRetracted No Change Extended Retract Actuator

In the table, a measured speed of greater than a first predeterminedthreshold (#1) of for example 10 to 35 mph with actuator 26 in theretracted position commands the actuator to move to its extendedposition. These speeds are associated with the threshold at which thesystem is capable of providing reductions in pedestrian impact injuries.In the event that the vehicle speed falls below a second predeterminedthreshold, i.e. about 8 mph (#2) and actuator 26 is in the extendedposition, the actuator is caused to retract grill 14. This would placegrill 14 in the retracted position in the normal resting condition ofthe vehicle while it is parked or when it is moving at a very low rateof speed. When the speed signal indicates a speed above a thirdpredetermined threshold, i.e. above about 37 mph (#3) and actuator 26 isin the extended position, it is caused to retract. This reflects thefact that minimal positive benefits are provided above this speed for animpacted pedestrian and retraction will serve to streamline the vehicleat higher vehicle speeds. Apparatus 10 may also be controlled usingother signal inputs, such as impact detection systems or manual driverinput to extend grill 14.

The extended position of grill 14 in the forward direction may beoptimized for a particular vehicle design. In one preferred embodiment,grill 14 in the extended position will extend beyond the front edge ofthe vehicle bumper 28 and retract to a position behind the bumper. Inother implementations, grill 14, while in the extended position will beat the forward position of bumper 28.

Pedestrian protection apparatus 10 is principally designed to deal withimpact loads generated by a motor vehicle in the 1,500 pound to 6,000pound range, traveling in the 8 mph to 35 mph range, and impacting asubstantially stationary pedestrian in the 25 pound to 250 pound range.This is contrasted to loads generated by vehicle-to-vehicle collisionsor by a vehicle impacting a stationary structure. Devices optimized forsuch vehicle-to-vehicle or single vehicle collisions with stationaryobjects would deform only an insignificant amount if exposed to thevehicle-to-pedestrian impact loads addressed by the present invention,thus providing little benefit for pedestrians.

Grill 14, when in the extended position, may also provide a signal whenan impact occurs to trigger other injury reducing mechanisms such ashood lifting devices which are presently known. For example, sensor 30may be coupled with actuator 16 to provide an output when it isaccelerated rapidly in response to a pedestrian impact.

While the above description constitutes the preferred embodiment of thepresent invention, it will be appreciated that the invention issusceptible to modification, variation and change without departing fromthe proper scope and fair meaning of the accompanying claims.

1. A pedestrian protection apparatus for a motor vehicle comprising: agrill affixed to the front end structure of the motor vehicle, anactuator coupled to the grill for moving the grill between a retractedposition and an extended position, with the grill in the extendedposition providing impact protection for a pedestrian impacted by themotor vehicle through energy absorption through retraction of the grillagainst the actuator, and a control unit for controlling the actuatorbased at least in part on the forward speed of the motor vehicle.
 2. Thepedestrian protection apparatus according to claim 1 wherein the motorvehicle further includes a bumper located below the grill, the grillpositioned forward of the bumper in the extended position and rearwardof the bumper in the retracted position.
 3. The pedestrian protectionapparatus according to claim 1 wherein the motor vehicle furtherincludes a bumper located below the grill, the grill positioned at theforward position of the bumper in the extended position and rearward ofthe bumper in the retracted position.
 4. (canceled)
 5. The pedestrianprotection apparatus according to claim 1 wherein the actuator comprisesa pinion gear driving a toothed rack with the toothed rack coupled withthe grill.
 6. The pedestrian protection apparatus according to claim 1wherein the actuator has elements which mechanically fail to provideenergy absorption upon the impacting of the motor vehicle with thepedestrian.
 7. The pedestrian protection apparatus according to claim 1wherein the actuator comprises at least two of the actuators areprovided for moving the grill.
 8. The pedestrian protection apparatusaccording to claim 1 wherein the grill includes apertures for vehicleheadlights.
 9. The pedestrian protection apparatus according to claim 1wherein the grill outside perimeter substantially encompasses thefrontal surface of the front end structure of the motor vehicle.
 10. Thepedestrian protection apparatus according to claim 1 wherein the controlunit responds to speed of the motor vehicle such that if the vehiclespeed is above a predetermined threshold and the grill is in theretracted position, the control unit causes the grill to move to theextended position.
 11. The pedestrian protection apparatus according toclaim 10 wherein the predetermined threshold is between 10 mph and 35mph.
 12. The pedestrian protection apparatus according to claim 1wherein the control unit responds to speed of the motor vehicle suchthat if the vehicle speed is below a predetermined threshold and thegrill is in the extended position, the control unit causes the grill tomove to the retracted position.
 13. The pedestrian protection apparatusaccording to claim 12 wherein the second predetermined threshold isabout 8 mph.
 14. The pedestrian protection apparatus according to claim1 wherein the control unit responds to speed of the motor vehicle suchthat if the vehicle speed is above a third predetermined threshold andthe grill is in the extended position, the control unit causes the grillto move to the retracted position.
 15. The pedestrian protectionapparatus according to claim 14 wherein the third predeterminedthreshold is about 37 mph.
 16. The pedestrian protection apparatusaccording to claim 1 further comprising an impact sensor coupled withthe apparatus to detect an impact with the grill in the extendedposition.
 17. The pedestrian protection apparatus according to claim 1wherein the pedestrian protection apparatus provides energy absorptionfor a pedestrian in the 25 pound to 250 pound range, struck by the motorvehicle in the 1500 pound to 6000 pound range, at a speed of the motorvehicle between 8 mph and 35 mph.
 18. The pedestrian protectionapparatus according to claim 1 wherein the control unit operatesautomatically without intervention by an occupant of the motor vehicle.19. A pedestrian protection apparatus for a motor vehicle comprising: agrill affixed to the front end structure of the motor vehicle above afront bumper of the motor vehicle, an actuator coupled to the grill formoving the grill between a retracted position and an extended positionwherein the apparatus provides energy absorption with the grill in theextended position upon the impacting of the motor vehicle with thepedestrian to reduce injury to the pedestrian through energy absorptionthrough retraction of the grill against the actuator, and a control unitfor controlling the actuator based at least in part on the forward speedof the motor vehicle.
 20. The pedestrian protection apparatus accordingto claim 19 wherein the grill is positioned forward of the bumper in theextended position and rearward of the bumper in the retracted position.21. The pedestrian protection apparatus according to claim 19 whereinthe grill positioned at the forward position of the bumper in theextended position and rearward of the bumper in the retracted position.22. The pedestrian protection apparatus according to claim 19 whereinthe actuator comprises a pinion gear driving a toothed rack with thetoothed rack coupled with the grill.
 23. The pedestrian protectionapparatus according to claim 19 wherein the actuator has elements whichmechanically fail to provide energy absorption upon the impacting of themotor vehicle with the pedestrian.
 24. The pedestrian protectionapparatus according to claim 19 wherein the actuator comprises at leasttwo of the actuators are provided for moving the grill.
 25. Thepedestrian protection apparatus according to claim 19 wherein the grillincludes apertures for vehicle headlights.
 26. The pedestrian protectionapparatus according to claim 19 wherein the grill outside perimetersubstantially encompasses the frontal surface of the front end structureof the motor vehicle.
 27. The pedestrian protection apparatus accordingto claim 19 wherein the control unit responds to speed of the motorvehicle such that if the vehicle speed is above a predeterminedthreshold and the grill is in the retracted position, the control unitcauses the grill to move to the extended position.
 28. The pedestrianprotection apparatus according to claim 27 wherein the predeterminedthreshold is between 10 mph and 35 mph.
 29. The pedestrian protectionapparatus according to claim 19 wherein the control unit responds tospeed of the motor vehicle such that if the vehicle speed is below apredetermined threshold and the grill is in the extended position, thecontrol unit causes the grill to move to the retracted position.
 30. Thepedestrian protection apparatus according to claim 29 wherein thepredetermined threshold is about 8 mph.
 31. The pedestrian protectionapparatus according to claim 19 wherein the control unit responds tospeed of the motor vehicle such that if the vehicle speed is above apredetermined threshold and the grill is in the extended position, thecontrol unit causes the grill to move to the retracted position.
 32. Thepedestrian protection apparatus according to claim 31 wherein thepredetermined threshold is about 37 mph.
 33. The pedestrian protectionapparatus according to claim 19 further comprising an impact sensorcoupled with the apparatus to detect an impact with the grill in theextended position.
 34. The pedestrian protection apparatus according toclaim 19 wherein the pedestrian protection apparatus provides energyabsorption for a pedestrian in the 25 pound to 250 pound range, struckby the motor vehicle in the 1500 pound to 6000 pound range, at a speedof the motor vehicle between 8 mph and 35 mph.
 35. The pedestrianprotection apparatus according to claim 19 wherein the control unitoperates automatically without intervention by an occupant of the motorvehicle.
 36. A pedestrian protection apparatus for a motor vehiclecomprising: a grill affixed to the front end structure of the motorvehicle, an actuator comprising a pinion gear driving a toothed rackwith the toothed rack coupled with the grill for moving the grillbetween a retracted position and an extended position, with the grill inthe extended position providing impact protection for a pedestrianimpacted by the motor vehicle, and a control unit for controlling theactuator based at least in part on the forward speed of the motorvehicle.
 37. A pedestrian protection apparatus for a motor vehiclecomprising: a grill affixed to the front end structure of the motorvehicle, an actuator coupled to the grill for moving the grill between aretracted position and an extended position, with the grill in theextended position providing impact protection for a pedestrian impactedby the motor vehicle, and a control unit for controlling the actuatorbased at least in part on the forward speed of the motor vehicle andresponding to speed of the motor vehicle such that if the vehicle speedis above a predetermined threshold and the grill is in the retractedposition, the control unit causes the grill to move to the extendedposition.
 38. The pedestrian protection apparatus according to claim 37wherein the predetermined threshold is between 10 mph and 35 mph.
 39. Apedestrian protection apparatus for a motor vehicle comprising: a grillaffixed to the front end structure of the motor vehicle, an actuatorcoupled to the grill for moving the grill between a retracted positionand an extended position, with the grill in the extended positionproviding impact protection for a pedestrian impacted by the motorvehicle, and a control unit for controlling the actuator based at leastin part on the forward speed of the motor vehicle wherein the controlunit responds to speed of the motor vehicle such that if the vehiclespeed is below a predetermined threshold and the grill is in theextended position, the control unit causes the grill to move to theretracted position.
 40. The pedestrian protection apparatus according toclaim 39 wherein the predetermined threshold is about 8 mph.
 41. Apedestrian protection apparatus for a motor vehicle comprising: a grillaffixed to the front end structure of the motor vehicle, an actuatorcoupled to the grill for moving the grill between a retracted positionand an extended position, with the grill in the extended positionproviding impact protection for a pedestrian impacted by the motorvehicle, and a control unit for controlling the actuator based at leastin part on the forward speed of the motor vehicle wherein the controlunit responds to speed of the motor vehicle such that if the vehiclespeed is above a predetermined threshold and the grill is in theextended position, the control unit causes the grill to move to theretracted position.
 42. The pedestrian protection apparatus according toclaim 41 wherein the predetermined threshold is about 37 mph.
 43. Apedestrian protection apparatus for a motor vehicle comprising: grillaffixed to the front end structure of the motor vehicle above a frontbumper of the motor vehicle, an actuator coupled to the grill for movingthe grill between a retracted position and an extended position, theapparatus having a pinion gear driving a toothed rack with the toothedrack coupled with the grill, wherein the apparatus provides energyabsorption with the grill in the extended position upon the impacting ofthe motor vehicle with the pedestrian to reduce injury to thepedestrian, and a control unit for controlling the actuator based atleast in part on the forward speed of the motor vehicle.
 44. Apedestrian protection apparatus for a motor vehicle comprising: a grillaffixed to the front end structure of the motor vehicle above a frontbumper of the motor vehicle, an actuator coupled to the grill for movingthe grill between a retracted position and an extended position whereinthe apparatus provides energy absorption with the grill in the extendedposition upon the impacting of the motor vehicle with the pedestrian toreduce injury to the pedestrian, and a control unit for controlling theactuator based at least in part on the forward speed of the motorvehicle wherein the control unit responds to speed of the motor vehiclesuch that if the vehicle speed is above a predetermined threshold andthe grill is in the retracted position, the control unit causes thegrill to move to the extended position.
 45. The pedestrian protectionapparatus according to claim 44 wherein the predetermined threshold isbetween 10 mph and 35 mph.
 46. A pedestrian protection apparatus for amotor vehicle comprising: a grill affixed to the front end structure ofthe motor vehicle above a front bumper of the motor vehicle, an actuatorcoupled to the grill for moving the grill between a retracted positionand an extended position wherein the apparatus provides energyabsorption with the grill in the extended position upon the impacting ofthe motor vehicle with the pedestrian to reduce injury to thepedestrian, and a control unit for controlling the actuator based atleast in part on the forward speed of the motor vehicle wherein thecontrol unit responds to speed of the motor vehicle such that if thevehicle speed is below a predetermined threshold and the grill is in theextended position, the control unit causes the grill to move to theretracted position.
 47. The pedestrian protection apparatus according toclaim 46 wherein the predetermined threshold is about 8 mph.
 48. Apedestrian protection apparatus for a motor vehicle comprising: a grillaffixed to the front end structure of the motor vehicle above a frontbumper of the motor vehicle, an actuator coupled to the grill for movingthe grill between a retracted position and an extended position whereinthe apparatus provides energy absorption with the grill in the extendedposition upon the impacting of the motor vehicle with the pedestrian toreduce injury to the pedestrian, and a control unit for controlling theactuator based at least in part on the forward speed of the motorvehicle wherein the control unit responds to speed of the motor vehiclesuch that if the vehicle speed is above a predetermined threshold andthe grill is in the extended position, the control unit causes the grillto move to the retracted position.
 49. The pedestrian protectionapparatus according to claim 48 wherein the predetermined threshold isabout 37 mph.